1. Field of the Invention
This invention relates to a method for manufacturing a metallic dental crown to be capped on a base formed on a tooth root in an oral cavity and a mold material for forming a dental crown occlusal portion used for the method.
2. Related Art
As one treatment of a carious tooth in an oral cavity, it has heretofore been known that a model base is made out of a base formed on a treated tooth root, then a metallic dental crown is made out of such obtained model base and then, the metallic dental crown is capped on the base using an adhesive agent. This metallic dental crown is made by a method using a wax mold shown in FIGS. 1(A) to 1(F).
In FIGS. 1(A) and 1(B), reference numeral 1 denotes a model base templated from a base formed on a tooth root in an oral cavity. First, as shown in FIG. 1(A), an entire peripheral surface including a top face and an outer peripheral surface, of the model base 1 is coated with wax to form a wax-coated layer 2a having a predetermined thickness.
Then, as shown in FIG. 1(B), an occlusal portion 3 having precision concavities and convexities are formed on the top face of the wax-coated layer 2a by cutting and an external configuration thereof is properly shaped. Then, a lower end portion (a marginal portion 4 contacting the gum) of the wax-coated layer 2a is cut to obtain a wax mold material 2b. 
Then, as shown in FIG. 1(C), the wax mold material 2b is removed from the model base 1 and a spool 5 is attached to the wax mold material 2b. 
Then, as shown in FIG. 1(D), the wax mold material 2b attached with the spool 5 is placed in a casting mold and molten metal 9 of gold, silver or the like is poured therein through the spool 5 to burn the wax mold material 2b so as to be substituted with the molten metal.
Hence, the metallic dental crown 7 as shown in FIG. 1(E) is accomplished. The metallic dental crown 7 thus obtained is, as shown in FIG. 1(F), capped on the base 8 in the oral cavity and firmly attached thereto by an adhesive agent.
However, the conventional dental crown manufacturing method has such problems that trained techniques and much time are required for the work for shaping the wax mold material 2b into a tooth shape, especially the work for cutting the precision occlusal shape 3 and as a consequence, the manufacturing cost for the metallic dental crown 7 is increased. In addition, uneven quality of the metallic dental crowns 7 is resulted.
It is, therefore, an object of the present invention to provide a novel method for manufacturing a metallic dental crown and a mold material for forming a dental crown occlusal portion used in the method, in which the above-mentioned problems inherent in the related art can be solved fundamentally.
To achieve the above object, from one aspect of the present invention, there is essentially provided a method for manufacturing a metallic dental crown comprising making a model base out of a base formed on a tooth root in an oral cavity; capping only a top portion of the model base with a mold material for forming a dental crown occlusal portion which is made of plastic film and which has a shallow royal crown configuration; coating that area of an outer peripheral surface of the model base, which is not capped with the mold material for forming the dental crown occlusal portion, with wax to form a composite mold material for forming the dental crown integral with the mold material for forming the dental crown occlusal portion; and substitution molding the composite mold material for forming the dental crown with a metal material.
From another aspect of the invention, there is also provided a mold material for forming a dental crown occlusal portion used for manufacturing a metallic dental crown, comprising a cover portion having an occlusal portion for covering a top face of a model base templated from a base formed on a tooth root in an oral cavity, an engagement portion standing down from a peripheral edge portion of the cover portion and engageable with a peripheral surface of a top portion of the model base, the cover portion and the engagement portion being formed from an integrally formed plastic film, the mold material for forming a dental crown occlusal portion exhibiting, as a whole, a shallow crown configuration.
It is preferred that a lower end face of the engagement portion has a shear plane generally orthogonal to a peripheral surface thereof.
By virtue of the construction of the present invention, the above-mentioned object of the present invention can be solved fundamentally.